Suzaku observations of Abell 1835 outskirts: Deviation from hydrostatic equilibrium. (arXiv:1302.0095v1 [astro-ph.CO])

Suzaku observations of Abell 1835 outskirts: Deviation from hydrostatic equilibrium. (arXiv:1302.0095v1 [astro-ph.CO]):
We present results of four-pointing Suzaku X-ray observations (total ~200 ks)
of the intracluster medium (ICM) in the Abell 1835 galaxy cluster (kT ~ 8 keV,
z = 0.253) out to the virial radius (r_vir ~ 2.9 Mpc) and beyond. Faint X-ray
emission from the ICM out to r_vir is detected. The temperature gradually
decreases with radius from ~8 keV in the inner region to ~2 keV at r_vir. The
entropy profile is shown to flatten beyond r_500, in disagreement with the
r_1.1 dependence predicted from the accretion shock heating model. The thermal
pressure profile in the range 0.3r_500 < r < r_vir agrees well with that
obtained from the stacked Sunyaev-Zel'dovich effect observations with the
Planck satellite. The hydrostatic mass profile in the cluster outskirts (r_500
< r < r_vir) falls well short of the weak lensing one derived from
Subaru/Suprime-Cam observations, showing an unphysical decrease with radius.
The gas mass fraction at r_vir defined with the lensing total mass agrees with
the cosmic baryon fraction from the WMAP 7-year data. All these results
indicate, rather than the gas-clumping effect, that the bulk of the ICM in the
cluster outskirts is far from hydrostatic equilibrium and infalling matter
retained some of its kinetic energy. Finally, combining with our recent Suzaku
and lensing analysis of Abell 1689, a cluster of similar mass, temperature, and
redshift, we show that the cluster temperature distribution in the outskirts is
significantly correlated with the galaxy density field in the surrounding
large-scale environment at (1-2)r_vir.